Pakistan's Shahid Afridi, Bangladesh's Habibul Bashar, England's Ian Bell, New Zealand's Shane Bond, Australia's Mike Hussey, Kumar Sangakkara of Sri Lanka and Graeme Smith of South Africa were unveiled as the other ambassadors for the tournament.
The announcement comes exactly 50 days before the first ball is bowled in the tournament-opener between England and Bangladesh at The Oval.
Harbhajan, who was a member of the India side which shared the 2002 trophy with Sri Lanka in Colombo, said he feels honoured.
"I am confident that team India will achieve greater heights and am sure that millions of fans back home will be following the side's fortunes."
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The eight Ambassadors, between them, have played 1,774 One-Day Internationals, scoring 51,906 runs with 48 centuries, and taking 838 wickets.
The Champion Ambassadors will be involved in the Champions Trophy Trophy Tour and will also make appearances in the UK.
ICC Chief Executive David Richardson said: "The programme will connect these greats of the game with a new generation of fans and players through our Cricket For Good project and leave a real lasting legacy for the sport."
Former Pakistan captain Afridi said it feels good to be part of an esteemed group.
"Three more Ambassadors and we would have made a tournament-winning side," he quipped.